1. Field of the Invention
This invention relates generally to tape cassettes and to the cassette holders of cassette tape recording and/or reproducing apparatus of the front-loading type in which tape cassettes of different sizes can be selectively employed.
2. Description of the Prior Art
In a known cassette tape recording and/or reproducing apparatus capable of selectively employing tape cassettes of different sizes, for example, as disclosed in U.S. Pat. No. 3,735,939, having a common assignee herewith, a cassette holder movable between a raised cassette receiving and discharging position and a lowered cassette loading position is provided with a single, substantially laterally centered guide rail that extends parallel to the direction in which a cassette is slidably inserted into, or removed from the holder with the latter in its raised position. Each cassette, whether of large size or small size, is provided with a substantially centered guide groove in its bottom surface for slidably receiving the guide rail of the holder when the respective cassette is inserted into the holder so as to correctly position the cassette relative to the holder.
It will be apparent that, in the foregoing arrangement according to the prior art, each of the cassettes of different sizes has to be provided with a substantially laterally centered guide groove in its bottom surfaces for suitably positioning either the small-sized or large-sized cassette in the cassette holder. However, many cassettes that are currently available commercially and could be economically used as the small- sized cassettes do not have an approximately laterally centered guide groove in the bottom surface and, hence, cannot be used in the described arrangement according to the prior art for permitting the use of cassettes of different sizes in a cassette tape recording and/or reproducing apparatus. Therefore, in order to use the currently commercially available cassettes as the relatively small-sized cassettes according to the known arrangement, each currently available cassette would have to be additionally processed to provide the laterally centered guide groove in its bottom surface. It is apparent that such additional processing of each currently available cassette would be both costly and difficult.